MWA Multiple Dispatchers Not Working And MWA Server Manager Shows Stopped Status

We notice that, all MWA servers are registering with the first Dispatcher and ignoring any other dispatchers which are up and running.

While starting, we might see messages like below:

MWA Telnet Server Release: 1.0.8.4 [December 12th 2002]
Port Number Dispatcher Will Be Started On: 10763
Port to use for this dispatcher: 10763
Port has probably been taken.
Error starting the Dispatcher.

Or The dispatcher logs might show like below:

Log from first Dispatcher
-------------------------
[Wed Oct 28 16:19:38 2020] runRegistrar: server registry full
[Wed Oct 28 16:19:38 2020] runRegistrar: server registry full
[Wed Oct 28 16:19:38 2020] runRegistrar: server registry full

 Log from second Dispatcher
-----------------------------
[Wed Oct 28 16:17:08 2020] Port to use for this dispatcher: 10300
[Wed Oct 28 16:17:08 2020] main: got local host name 'atgmwa.us.oracle.com'
[Wed Oct 28 16:17:08 2020] main: listener server socket created
[Wed Oct 28 16:17:08 2020] main: created worker threads with connections
[Wed Oct 28 16:17:08 2020] main: created registrar thread
[Wed Oct 28 16:17:08 2020] runRegistrar: registrar server socket created
[Wed Oct 28 16:17:39 2020] main: no servers available
[Wed Oct 28 16:19:42 2020] main: no servers available
[Wed Oct 28 16:19:47 2020] main: no servers available

 It could be happening when you try to configure multiple dispatchers.

Solution:

 1) Shut down all the MWA services including dispatcher

2) Navigate to $ADMIN_SCRIPTS_HOME

cd $ADMIN_SCRIPTS_HOME

3) Edit the mwactl.sh as follows:

FROM:
${MWA_TOP}/bin/MWADIS

TO:
${MWA_TOP}/bin/MWADIS -p "$2"

4) Start MWA services and start dispatchers as below

mwactl.sh start_dispatcher  <port#> &  

How to Configure multiple (MSCA) MWA dispatchers in EBS?

At times, we get a requirement to configure multiple dispatchers or additional ports for (MSCA) MWA in EBS. We can follow below steps to do the same.

Identify the file mwa.cfg located under $INST_TOP/admin/install.

Update the following fields in mwa.cfg file.

#Update the following parameter with the MWA ports you want to use for telnet. Example below:

mwa.TelnetPortNumber=10220,10222,10224,10226,10228,10230,10232,10234,10236,10238,10240,10242,10244,10246,10248,10250,10252,10254,10256,10258

# Specify the port number and machine for running the dispatcher
# For eg. mwa.Dispatcher = ap100sun:2300
mwa.Dispatcher=locahost:10753,localhost:10763

We need to enter the dispatcher ports we want to use in the mwa.Dispatcher parameter in mwa.cfg file as mentioned in above example.

Now, once this is done, go to $ADMIN_SCRIPTS_HOME and modify the mwactl.sh file as below:

FROM:
${MWA_TOP}/bin/MWADIS

TO:
${MWA_TOP}/bin/MWADIS -p "$2"

Note: If we do not update mwactl.sh with above change, dispatcher will start on only one port. 

To retain these changes and to avoid being overwritten during autoconfig, perform the below.

Go to $MWA_TOP/admin/template

create a folder called custom 

copy the files mwa.cfg and mwactl.sh to custom folder.

Edit them as mentioned in above steps. This will make sure the autoconfig would still retain the changes we have done.